Hybrid vehicles have been proposed in an attempt to improve fuel economy at least partly in view of adverse environmental effects. Several hybrid vehicles are known that utilize a gasoline engine, an electric motor, and a battery to power a traction wheel. Several types of gasoline electric hybrid vehicles are disclosed in U.S. Pat. No. 7,455,134.
One type of gasoline electric hybrid vehicle does not receive electricity from a source external of the vehicle but utilizes a mechanism that allows the gasoline engine to recharge the battery. The battery stores energy for at least partially powering an electric motor and the vehicle controller determines and signals the proportion of power that should be generated by the electric motor and the gasoline engine based on a given set of circumstances. Some of these hybrid vehicles that do not receive external electricity can travel only short distances while being powered by only the electric motor.
The present inventors recognize that it would be desirable expand the usage of the electric motor of a hybrid vehicle. Some systems used to expand the usage of the electric motor also modify the vehicle to allow the vehicle to obtain electricity from a source other than that generated by a generator connected to the gasoline engine. In plug-in hybrid conversion systems, such electric sources may be external of the vehicle allowing the vehicle to be connected to an external electric source, such as an electric power grid.
Conversion systems, such as plug-in hybrid conversion systems for use with hybrid vehicles, like the Toyota Prius, can rely on three devices or methods of utilizing the electric motor rather than engine. According to the first method, a plug-in hybrid controller requests an electric only mode from the vehicle's main hybrid control computer (H-ECU). This method limits the vehicle's speed, for example to 34 mph on a Prius. In one type of hybrid vehicle, the H-ECU has a stock electric only mode. The H-ECU limits the speed of the vehicle to 34 mph when in electric only mode. Any conversion device using the stock mode of the H-ECU is limited to a maximum vehicle speed of 34 mph in all electric mode. The first method is limited by other operational factors, such as, battery temperature, battery charge current limit, gasoline engine temperature, and accelerator position. The first method does not provide for a mode of warming up the engine before the engine is used when switching out of electric only mode. This causes higher controlled emissions from the engine due to cold starts of the gasoline engine.
A second method alters battery charge messages being sent to the H-ECU. The battery charge messages are altered to indicate a different state of charge of the traction battery than is the actual state of charge and therefore the H-ECU responds by increasing the usage of the electric motor over the gasoline motor. This second method limits the amount of electricity utilized because in one type of hybrid vehicle if a high state of battery charge is signaled or reported to the H-ECU, the H-ECU will only use up to about 7 kilowatts of electricity to power the motor for a sustained period.
A third method forces the gasoline engine to turn off or remain off by disconnecting the engine computer (E-ECU) from the H-ECU or by powering off the E-ECU. The disconnection is achieved by physically disconnecting the E-ECU or by providing an electronic switch. This third method causes the vehicle to generate diagnostic trouble codes. These trouble codes may require the operator cycle the vehicle off and back on to restart the gasoline engine. Restarting the vehicle is often not practical, and under some circumstances, not safe. This method may also require frequent clearing of the diagnostic trouble codes from the vehicle computer system, which may prohibit the vehicle from meeting many clean air regulations. Moreover, under the third method, the vehicle is limited to 42 mph when the motor is operating within its rated safety speed.
A Hybrid Vehicle
The control device of the invention operates in a hybrid vehicle 50, such as for example that disclosed in U.S. Pat. No. 6,520,160 issued Feb. 18, 2003, which is incorporated by reference except to the extent modified herein. FIG. 1 based on FIG. 1 of U.S. Pat. No. 6,520,160 shows a schematical view of one type of hybrid vehicle 50. The vehicle has two drive sources. The drive sources are an internal combustion engine 1 and an electric motor 2. The engine has a water temperature sensor 18 that provides an electric signal corresponding to the temperature of the cooling water of the engine 1.
The engine discharges exhaust air from the combustion cylinders through an exhaust discharge pipe 13. An emission gas purifying catalyzer 14 for purifying harmful gas component in emission gas is provided in the discharge pipe 13. The emission gas purifying catalyzer or catalytic converter 14 may be provided with a catalyzer temperature sensor 15 for outputting an electric signal corresponding to the temperature of the emission gas purifying catalyzer 14.
A crank shaft, which is an output shaft of the internal combustion engine 1, is coupled with an output shaft 1a and the output shaft 1a is coupled with a drive power dividing mechanism 4. The drive power dividing mechanism 4 is mechanically connected to a power generator 3 and a rotation shaft (motor rotation shaft) 2a of an electric motor 2.
The drive power dividing mechanism 4 is comprised of, for example, planetary carrier supporting a pinion gear freely rotatably, ring gear disposed outside the planetary carrier, and planetary gear having a sun gear disposed inside the planetary carrier. A rotation shaft of the planetary carrier is coupled with the output shaft 1a, the rotation shaft of the ring gear is coupled with the rotation shaft 2a of the motor, and the rotation shaft of the sun gear is coupled with the power generator 3. The power dividing mechanism 4 is further explained in U.S. Pat. No. 7,486,034 where it is described as a power split device, which is incorporated by reference.
The power generator 3 is incorporated in the hybrid vehicle for operating as an electric generator driven by the engine and operating as an electric motor capable of starting the engine, while motor 2 is incorporated in the hybrid vehicle for serving as an electric motor that drives a driving wheel of the hybrid vehicle.
A reduction gear 7 is coupled with the rotation shaft 2a of the electric motor 2 and wheels, which are driving wheels, are coupled with the reduction gear 7 through drive shafts 8, 9. The reduction gear 7 is constituted by combining plural gears and reduces a rotation speed of the rotation shaft 2a and transmits it to the drive shafts 8, 9.
The power generator 3 is connected electrically to an inverter 5 and the inverter 5 is electrically connected to a battery 6 and the electric motor 2. The battery 6 is provided with a battery controller 16 for calculating a state of charge of the battery 6.
The electric motor 2 may comprise an AC synchronous motor and, if an electric power generated by the power generator 3 and/or electric power from the battery 6 is applied, the rotation shaft 2a of the motor is rotated at a torque corresponding to the magnitude of applied electric power.
The vehicle 50 has an electronic control unit (E-ECU) 23 for controlling the internal combustion engine 1 and a vehicle electronic control unit (H-ECU) 24 for controlling the entire hybrid mechanism synthetically. These E-ECU 23 and H-ECU 24 are connected to each other through an interactive communication line or communication bus 52.
A catalyzer temperature sensor 15, a crank position sensor 17, a water temperature sensor 18, a throttle position sensor 19a, air-fuel ratio sensor 27, an air flow meter 31 and the like are connected to the E-ECU 23 through electric wiring so that output signals from the respective sensors are inputted to the E-ECU 23.
A throttle actuator 19b, an ignition plug 25 and a fuel injection valve 26 are connected to the E-ECU 23 through electric wiring so that a control signal can be transmitted from the E-ECU 23 to the throttle actuator 19b, the ignition plug 25 and the fuel injection valve 26.
The battery controller 16, an accelerator position sensor 29 for outputting an electric signal corresponding to an operating amount (accelerator opening degree) of the accelerator pedal 28 mounted in the vehicle compartment, a vehicle speed sensor 30 for outputting an electric signal corresponding to a traveling speed of the vehicle and the like are connected to the H-ECU 24 through electric wiring and output signal of each sensor is inputted to the H-ECU 24.
The H-ECU 24 is connected to the electric motor 2, the power generator 3, and the inverter 5 through electric wiring so that a control signal can be transmitted from the H-ECU 24 to the electric motor 2, the power generator 3 and the inverter 5.
In the control system having such a structure, the H-ECU 24 controls the electric motor 2, the power generator 3, and the inverter 5 according to output signals from the accelerator position sensor 29, the battery controller 16 and the like and sends messages or signals through the communication line 52 to control the internal combustion engine 1 through the E-ECU 23. While the foregoing demonstrates one type of hybrid vehicle, the inventors recognize it would be desirable to have a device that is not limited to use with one type or model of hybrid vehicle.
Engine Warmup and Emissions
Generally, vehicle emissions are evaluated by placing the test car on a dynamometer (dyno) where the dynamometer simulates the vehicle being driven by driving a predetermined route, called a dyno drive cycle or drive schedule. A common drive cycle is the urban dyno drive schedule (UDDS). Normally the ignition of the car is pressed and the test will start about 12-15 seconds after the ignition has been pressed before entering a gentle hill. This gives the car time to go through a controlled warm up of the engine and exhaust catalyst while stopped and at low engine power on the first hill. While this test accurately measures emissions produced, it does not necessarily represent real-world conditions where a driver starts the car and accelerates moderately or quickly before the car has a chance to warm up the catalyst. This real-world example leads to worse emissions over that emitted in the urban dyno drive.
A problem arising when modifying certain hybrid vehicles, such as to allow it to receive power from a source external of the vehicle and to operate only powered only by the electric motor, is that it is possible to start the car in an electric mode only, where the gas engine is not started and not warmed up, and thus the catalyst or catalytic converter is never heated. When either the battery depletes or the driver demands more power than the electric mode can supply, the gas engine is started suddenly. When this occurs, the gas engine is run at high power before the catalyst is warmed up leading to increased emissions.
The present inventors recognize that it would be advantageous to provide a device and method configured to allow the gasoline engine to go through a proper warm up cycle while the vehicle is powered by the electric motor only.
The present inventors recognize that it would be advantageous to provide a device and method configured to shut down the gasoline engine and or prevent the gasoline engine from starting and allow the vehicle to be powered by the electric motor. The inventors recognize that it would be advantageous to provide a device and method configured to allow the vehicle's main hybrid controller to supplement a lack of gasoline engine power with increased electric power and without causing diagnostic trouble codes to be generated.
The present inventors recognize that it would be advantageous to provide a device and method configured to allow a hybrid vehicle to use more than 7 kilowatts of electricity for a sustained period. The present inventors recognize that it would be advantageous to provide a device and method configured to allow a hybrid vehicle to use at least about 25 kilowatts or more of electricity for a sustained period.
The present inventors recognize that it would be advantageous to provide a device and method configured to allow the gas engine to be run at different speeds or revolutions per minute (RPM) and different power output than requested by the main hybrid controller in order to change balance of power generated between the gasoline engine and the electric motor.